This is the story of Sister Catherine Anne Cesnik, who was murdered on November 7, 1969 in Baltimore, Maryland. She was 26-years-old, and a beloved English teacher at an all-girls Catholic high school. Cesnik's murder was never solved, but instead became the key used to unlock a terrifying closet of secrets hidden within the walls of Archbishop Keough High School, centered around one man, the school chaplain, Rev. A. Joseph Maskell.

The question on everyone's mind since her body was discovered in January 3, 1970 is a simple one: "Who killed Cathy Cesnik?" Well, before that information comes to light (which, following the recent exhumation of Maskell's body could very well happen), it first matters what exactly that this young nun knew that could have contributed to her death.

Ahead, we get into exactly what Sister Cathy knew at the time of her disappearance and murder.